Laser Plug and Abandon Method

ABSTRACT

A well is abandoned by locating a plug in casing preferably at a location above where the quality of the cement job or the casing is questionable. A high powered laser is run in preferably on wireline and at a location above the plug is activated and rotated with the effect that the casing, cement behind the casing and the formation about the cement becomes molten and flows onto the plug where the mass cools and solidifies into a cohesive mass that spans the borehole and extends laterally into the formation. The mass is impervious and the abandonment procedure is complete. The plug can be bare or it can have layers above such as cement to protect the plug from molten temperatures until the mass cools sufficiently and solidifies.

FIELD OF THE INVENTION

The field of the invention is plugging and abandoning wells and more particularly techniques for using laser technology to create a molten plug that solidifies into a barrier that spans one or more nested tubulars and potentially the surrounding formation.

BACKGROUND OF THE INVENTION

Lasers have been used in a plug and abandon context but only in the sense of tubular cutting to remove a string above a cut location so that plugs can then be placed for the abandonment. This technique is described in WO/2013/019959A2 employs high powered lasers for cutting one or more concentric tubulars for removal so that the plug can be put into position. This reference goes on to incorporate related cases by reference in paragraph 101. Other applications focus on the use of high powered lasers for perforating or fracturing the formation in a particular manner as illustrated in US 20130228372.

The present invention is focused on plugging and abandoning wells and the formation of a plug that can isolate a wellbore in a manner that meets or exceeds local regulations for sealing integrity. The plug is made with a high powered laser that is deployed in conjunction with a support platform that is run is and secured before the laser is activated and rotated to literally melt the tubular and cement behind the tubular and part of the formation behind the cement. The melted materials are stopped by the support platform in a molten state. The materials then cool off and form a cohesive whole that spans the borehole and continues into the void left by the melted cement and formation material so that on fully cooling the hardened whole sealingly spans the bore of the tubular in the location where the tubular melted and extends radially further into the cement and formation space that also was previously melted. Those skilled in the art will appreciate these and other aspects of the present invention from a review of the detailed description of the preferred embodiment and the associated drawings while appreciating that the full scope of the invention is to be determined by the appended claims.

SUMMARY OF THE INVENTION

A well is abandoned by locating a plug in casing preferably at a location above where the quality of the cement job or the casing is questionable and across from an impermeable and competent rock formation. A high powered laser is run in preferably on wireline and at a location above the plug is activated and rotated with the effect that the casing, cement behind the casing and the formation about the cement becomes molten and flows onto the plug where the mass cools and solidifies into a cohesive mass that spans the borehole and extends laterally into the formation. The mass is impervious and the abandonment procedure is complete. The plug can be bare or it can have layers above such as cement to protect the plug from molten temperatures until the mass cools sufficiently and solidifies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional elevation view of the wellbore with a plug in place before the laser is operated; and

FIG. 2 is the view of FIG. 1 after the laser is operated to create the cohesive plug for well abandonment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a borehole with upper casing 10 with cement 12 around it. Casing 14 is within casing 10 and another cement layer 16 is in between. Casing 18 is within casing 14 and is surrounded by cement 20. A liner 22 is hung off casing 18 with a liner hanger/packer 24 and is cemented with cement 26. A lower completion has perforations 28 through cement 26. Liner 22 has a problem such as an opening 30 and a pathway through cement 26 represented by arrow 32. Production fluids can come back through opening 34 in liner 22 while bypassing the liner hanger/packer 24. There is thus a leak path for formation fluids from zone 36 and ultimately into the borehole 38.

As part of the abandonment for this well a barrier such as a bridge plug or packer or other barrier device 40 is placed in liner 22. The illustration is schematic and the barrier 40 can be a single or multiple bridge plugs or packers and can optionally have a layer of one or more materials such as sand and then cement or other materials that are intended to act as a temporary barrier to molten material that will be created with the laser 42 delivered into the position shown with a wireline 44. The laser 42 can be pumped down or moved with a tractor to get it in position in horizontal wells.

FIG. 2 illustrates what happens when the laser 42 is activated and rotated. The liner 22 and cement 26 and the adjacent formation 52 are all raised to melting temperature and the molten mass then flows onto support assembly 40. As the molten mass cools and solidifies into a cohesive mass 50 a unitary solid mass is formed that spans the bore 38 and laterally extends further beyond liner 22 and the formation 52. Preferably the formation 52 is selected for the location of the plug assembly 40 with the plug 40 being a short distance below the ultimate depth of the laser so that the laser 42 is aligned with the formation 52 which is preferably impermeable.

The laser 42 is commercially available for downhole use and is enclosed in a suitable cover to shield the unit from well fluids or pressures and heat. Fluid circulation or movement represented by arrow 60 can be initiated to provide cooling to the laser 42 and the molten mass 50 to accelerate cooling the mass 50 and the formation of the barrier. The laser 42 can be anchored to the liner 22 and rotated with an associated motor all intended to be schematically depicted in item 42.

Those skilled in the art will now appreciate that the use of the laser allows the formation of a cohesive impervious mass that spans the borehole as well as cement and into the surrounding formation such that the barrier is firmly planted and sealed so that anything that was wrong further downhole is totally isolated in a permanent manner to meet regulations from governmental authorities around the world. The extent of the melting into the formation is a function of the operation of the laser tool and the available energy input to the laser.

The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: 

I claim:
 1. A plug and abandon method, comprising: providing a support in a borehole to be plugged and abandoned; operating a laser adjacent said support; melting a tubular wall circumferentially with said laser; extending the melting beyond said tubular wall with said laser; supporting the melted mass on said support until solidification into an anchored plug; spanning said borehole with said solidified mass.
 2. The method of claim 1, comprising: using a packer or bridge plug as said support.
 3. The method of claim 1, comprising: using at least one of sand and cement as said support.
 4. The method of claim 1, comprising: melting cement outside said tubular with said laser.
 5. The method of claim 1, comprising: melting part of the formation outside said tubular with said laser.
 6. The method of claim 1, comprising: melting cement and a surrounding formation outside said tubular with said laser.
 7. The method of claim 1, comprising: severing said tubular and melting beyond said severed tubular to create a molten mass.
 8. The method of claim 7, comprising: severing and melting for a range of 360 degrees.
 9. The method of claim 2, comprising: using at least one of sand and cement as said support.
 10. The method of claim 1, comprising: rotating said laser during operation thereof.
 11. The method of claim 1, comprising: running in said laser on wireline.
 12. The method of claim 10, comprising: positioning said laser with flow or a tractor into a horizontal borehole.
 13. The method of claim 1, comprising: circulating fluid through the borehole while operating said laser.
 14. The method of claim 1, comprising: creating a molten mass in the borehole supported by said support until said mass solidifies and spans beyond said borehole.
 15. The method of claim 14, comprising: melting cement outside said tubular with said laser.
 16. The method of claim 15, comprising: melting part of the formation outside said tubular with said laser.
 17. The method of claim 16, comprising: severing said tubular and melting for a range of 360 degrees.
 18. The method of claim 17, comprising: using at least one of sand and cement as said support.
 19. The method of claim 18, comprising: circulating fluid through the borehole while operating said laser. 